Refrigerant cycle system

ABSTRACT

A refrigerant cycle system includes: a first refrigerant circuit; a second refrigerant circuit independent of the first refrigerant circuit; a heat source-side unit that includes a first heat source-side heat exchange unit and a second heat source-side heat exchange unit; a first use-side unit that includes a first use-side heat exchanger; a first liquid refrigerant connection pipe and a first gas refrigerant connection pipe that connect the first use-side unit to the heat source-side unit; a second use-side unit that includes a second use-side heat exchanger; and a second liquid refrigerant connection pipe and a second gas refrigerant connection pipe that connect the second use-side unit to the heat source-side unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of International Patent Application No. PCT/JP2020/043435, filed on Nov. 20, 2020, and claims priority to Japanese Patent Application No. 2019-212279, filed on Nov. 25, 2019, Japanese Patent Application No. 2019-212280, filed on Nov. 25, 2019, and Japanese Patent Application No. 2019-212281, filed on Nov. 25, 2019. The content of these priority applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a refrigerant cycle system.

BACKGROUND

Conventionally, a refrigerant cycle system including one refrigerant circuit configured by connecting a plurality of indoor units to one outdoor unit has been used.

For example, in a multi-room air conditioning apparatus described in Patent Literature 1 (JP 2011-257097 A), it is proposed to execute air conditioning in each room by using a refrigerant circuit in which a plurality of indoor units provided in rooms different from each other is connected to an outdoor unit.

SUMMARY

A refrigerant cycle system according to one or more embodiments includes a first refrigerant circuit and a second refrigerant circuit independent of the first refrigerant circuit, and includes a heat source-side unit, a first use-side unit, a first liquid refrigerant connection pipe, a first gas refrigerant connection pipe, a second use-side unit, a second liquid refrigerant connection pipe, and a second gas refrigerant connection pipe. The heat source-side unit includes a heat source-side heat exchanger. The heat source-side heat exchanger includes a first heat source-side heat exchange unit constituting part of the first refrigerant circuit and a second heat source-side heat exchange unit constituting part of the second refrigerant circuit. The first use-side unit includes a first use-side heat exchanger constituting part of the first refrigerant circuit. The first liquid refrigerant connection pipe connects the first use-side unit to the heat source-side unit and constitutes part of the first refrigerant circuit. The first gas refrigerant connection pipe connects the first use-side unit to the heat source-side unit and constitutes part of the first refrigerant circuit. The second use-side unit includes a second use-side heat exchanger constituting part of the second refrigerant circuit. The second liquid refrigerant connection pipe connects the second use-side unit to the heat source-side unit and constitutes part of the second refrigerant circuit. The second gas refrigerant connection pipe connects the second use-side unit to the heat source-side unit and constitutes part of the second refrigerant circuit. A refrigerant classified by ISO817 as lower flammability (A2L) is charged into each of the first refrigerant circuit and the second refrigerant circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of an air conditioning apparatus of a first embodiment.

FIG. 2 is a schematic explanatory diagram of an outdoor heat exchanger of the first embodiment.

FIG. 3 is a schematic explanatory diagram describing a refrigerant flow of the outdoor heat exchanger when a heating operation is executed in a second refrigerant circuit of the first embodiment.

FIG. 4 is a schematic explanatory diagram of an outdoor heat exchanger according to a modification D of the first embodiment.

FIG. 5 is a schematic configuration diagram of an air conditioning apparatus according to a modification E of the first embodiment.

FIG. 6 is an external perspective view of an outdoor unit of a second embodiment.

FIG. 7 is an arrangement explanatory diagram of shutoff valves of the outdoor unit of the second embodiment.

FIG. 8 is an arrangement explanatory diagram of shutoff valves of an outdoor unit according to a modification B of the second embodiment.

FIG. 9 is a schematic explanatory diagram of an outdoor heat exchanger of a third embodiment.

DETAILED DESCRIPTION

(1) Configuration of Air Conditioning Apparatus of First Embodiment

An air conditioning apparatus 1 will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of the air conditioning apparatus 1 according to the first embodiment of the present disclosure. The air conditioning apparatus 1 (one example of refrigerant cycle system) has two refrigeration cycles including a first refrigerant circuit 10 and a second refrigerant circuit 20, which are two independent refrigerant circuits that prevent a refrigerant from moving back and forth between each other. The air conditioning apparatus 1 of the first embodiment is an apparatus that cools and heats air conditioning target space by executing a vapor compression refrigeration cycle in each of the first refrigerant circuit 10 and the second refrigerant circuit 20.

The air conditioning apparatus 1 mainly includes, as shown in FIG. 1, an outdoor unit 2, a first indoor unit 6, a second indoor unit 7, a third indoor unit 8, and a fourth indoor unit 9 as a plurality of indoor units, a first liquid-side refrigerant connection pipe 65, a first gas-side refrigerant connection pipe 66, a second liquid-side refrigerant connection pipe 75, a second gas-side refrigerant connection pipe 76, a third liquid-side refrigerant connection pipe 85, a third gas-side refrigerant connection pipe 86, a fourth liquid-side refrigerant connection pipe 95, a fourth gas-side refrigerant connection pipe 96, and a control unit 50.

The first indoor unit 6 and the outdoor unit 2 constitute part of the first refrigerant circuit 10 by connection via the first liquid-side refrigerant connection pipe 65 and the first gas-side refrigerant connection pipe 66. The second indoor unit 7 and the outdoor unit 2 constitute part of the first refrigerant circuit 10 by connection via the second liquid-side refrigerant connection pipe 75 and the second gas-side refrigerant connection pipe 76. In this way, the first refrigerant circuit 10 is configured by connecting the first indoor unit 6 and the second indoor unit 7 in parallel to the outdoor unit 2. R32, which is a refrigerant classified by ISO817 as lower flammability (A2L), is charged into the first refrigerant circuit 10 such that the amount is less than 1.84 kg.

The third indoor unit 8 and the outdoor unit 2 constitute part of the second refrigerant circuit 20 by connection via the third liquid-side refrigerant connection pipe 85 and the third gas-side refrigerant connection pipe 86. The fourth indoor unit 9 and the outdoor unit 2 constitute part of the second refrigerant circuit 20 by connection via the fourth liquid-side refrigerant connection pipe 95 and the fourth gas-side refrigerant connection pipe 96. In this way, the second refrigerant circuit 20 is configured by connecting the third indoor unit 8 and the fourth indoor unit 9 in parallel to the outdoor unit 2. R32, which is a refrigerant classified by ISO817 as lower flammability (A2L), is charged into the second refrigerant circuit 20 as well such that the amount is less than 1.84 kg.

A pipe with an outer diameter of 6.35 mm and an inner diameter of less than 4.75 mm is used in all the first liquid-side refrigerant connection pipe 65, the second liquid-side refrigerant connection pipe 75, the third liquid-side refrigerant connection pipe 85, and the fourth liquid-side refrigerant connection pipe 95. Specifically, the pipe has the same outer diameter as nibukan, which is widely distributed as a refrigerant pipe used for a refrigerant circuit of an air conditioning apparatus, and has a smaller inner diameter than nibukan. With this configuration, when the use of nibukan, which has been widely used in the past, causes the inner diameter to be too large, the inner diameter can be reduced to an appropriate size, and it is easy to reduce the amount of refrigerant charged into the first refrigerant circuit 10 and the second refrigerant circuit 20. Therefore, even if a refrigerant leak occurs, it is possible to reduce the amount of leak. By setting the outer diameter to the same diameter as nibukan, which has been widely used in the past, it is possible to improve the diversion of tools used based on the outer diameter. For the first gas-side refrigerant connection pipe 66, the second gas-side refrigerant connection pipe 76, the third gas-side refrigerant connection pipe 86, and the fourth gas-side refrigerant connection pipe 96, an appropriate refrigerant pipe is used that is larger than nibukan, which is widely distributed as a refrigerant pipe used for a refrigerant circuit of an air conditioning apparatus, thereby reducing the pressure loss when the gas refrigerant passes.

(1-1) Outdoor Unit

The outdoor unit 2 is installed outside the air conditioning target space, for example, on the roof of a building, near a wall surface of a building, or the like.

The outdoor unit 2 includes part of the first refrigerant circuit 10, part of the second refrigerant circuit 20, an outdoor heat exchanger 30 commonly used for the first refrigerant circuit 10 and the second refrigerant circuit 20, and an outdoor fan 30 a.

The outdoor fan 30 a is one fan for supplying outdoor air to the outdoor heat exchanger 30, which is commonly used for the first refrigerant circuit 10 and the second refrigerant circuit 20. The outdoor fan 30 a is controlled to be driven by the control unit 50 in an operating state in which a refrigerant is flowing through either the first refrigerant circuit 10 or the second refrigerant circuit 20.

The first refrigerant circuit 10 mainly includes a first compressor 11, a first four-way switching valve 12, a first accumulator 13, the outdoor heat exchanger 30, a first liquid pipe 14 a, a second liquid pipe 14 b, a first expansion valve 15 a, a second expansion valve 15 b, a first liquid-side shutoff valve 16 a, a second liquid-side shutoff valve 16 b, a first gas pipe 17 a, a second gas pipe 17 b, a first gas-side shutoff valve 18 a, and a second gas-side shutoff valve 18 b.

A first port, which is one of connection ports of the first four-way switching valve 12, is connected to a suction side of the first compressor 11 via the first accumulator 13. A second port, which is one of connection ports of the first four-way switching valve 12, is connected to a discharge side of the first compressor 11. A refrigerant pipe extending toward the outdoor heat exchanger 30 is connected to a third port, which is one of connection ports of the first four-way switching valve 12. A refrigerant pipe extending toward the first gas-side shutoff valve 18 a and the second gas-side shutoff valve 18 b is connected to a fourth port, which is one of connection ports of the first four-way switching valve 12. The refrigerant pipe is branched into the first gas pipe 17 a and the second gas pipe 17 b. The first gas-side shutoff valve 18 a is provided at an end of the first gas pipe 17 a. The second gas-side shutoff valve 18 b is provided at an end of the second gas pipe 17 b. In the first refrigerant circuit 10, a refrigerant pipe connected to the opposite side of the first four-way switching valve 12 side across the outdoor heat exchanger 30 is branched into the first liquid pipe 14 a and the second liquid pipe 14 b. The first expansion valve 15 a is provided in the middle of the first liquid pipe 14 a, and the first liquid-side shutoff valve 16 a is provided at an end of the first liquid pipe 14 a. The second expansion valve 15 b is provided in the middle of the second liquid pipe 14 b, and the second liquid-side shutoff valve 16 b is provided at an end of the second liquid pipe 14 b.

By the control unit 50 switching the connection state of the first to fourth ports, the first four-way switching valve 12 can be switched between a cooling operation state in which the refrigerant discharged from the first compressor 11 is sent to the outdoor heat exchanger 30 (see the broken line in the first four-way switching valve 12 in FIG. 1), and a heating operation state in which the first compressor 11 sucks the refrigerant flowing from the outdoor heat exchanger 30 (see the solid line in the first four-way switching valve 12 in FIG. 1). When a predetermined defrosting start condition is satisfied while a heating operation is being executed in the first refrigerant circuit 10, the control unit 50 switches the connection state of the first four-way switching valve 12 from the heating operation state to the cooling operation state to execute a reverse cycle defrost operation. Then, when a predetermined defrosting end condition is satisfied, the control unit 50 returns the connection state of the first four-way switching valve 12 to the heating operation state again, and restores the heating operation in the first refrigerant circuit 10. Note that the predetermined defrosting start condition is not limited, but for example, if an outside air temperature sensor and a temperature sensor disposed below the outdoor heat exchanger 30 are installed, defrosting start may be determined based on the detection temperature of these temperature sensors.

The second refrigerant circuit 20 mainly includes a second compressor 21, a second four-way switching valve 22, a second accumulator 23, the outdoor heat exchanger 30, a third liquid pipe 24 a, a fourth liquid pipe 24 b, a third expansion valve 25 a, a fourth expansion valve 25 b, a third liquid-side shutoff valve 26 a, a fourth liquid-side shutoff valve 26 b, a third gas pipe 27 a, a fourth gas pipe 27 b, a third gas-side shutoff valve 28 a, and a fourth gas-side shutoff valve 28 b.

A fifth port, which is one of connection ports of the second four-way switching valve 22, is connected to a suction side of the second compressor 21 via the second accumulator 23. A sixth port, which is one of connection ports of the second four-way switching valve 22, is connected to a discharge side of the second compressor 21. A refrigerant pipe extending toward the outdoor heat exchanger 30 is connected to a seventh port, which is one of connection ports of the second four-way switching valve 22. A refrigerant pipe extending toward the third gas-side shutoff valve 28 a and the fourth gas-side shutoff valve 28 b is connected to an eighth port, which is one of connection ports of the second four-way switching valve 22. The refrigerant pipe is branched into the third gas pipe 27 a and the fourth gas pipe 27 b. The third gas-side shutoff valve 28 a is provided at an end of the third gas pipe 27 a. The fourth gas-side shutoff valve 28 b is provided at an end of the fourth gas pipe 27 b. In the second refrigerant circuit 20, a refrigerant pipe connected to the opposite side of the second four-way switching valve 22 side across the outdoor heat exchanger 30 is branched into the third liquid pipe 24 a and the fourth liquid pipe 24 b. The third expansion valve 25 a is provided in the middle of the third liquid pipe 24 a, and the third liquid-side shutoff valve 26 a is provided at an end of the third liquid pipe 24 a. The fourth expansion valve 25 b is provided in the middle of the fourth liquid pipe 24 b, and the fourth liquid-side shutoff valve 26 b is provided at an end of the fourth liquid pipe 24 b.

By the control unit 50 switching the connection state of the fifth to eighth ports, the second four-way switching valve 22 can be switched between the cooling operation state in which the refrigerant discharged from the second compressor 21 is sent to the outdoor heat exchanger 30 (see the broken line in the second four-way switching valve 22 in FIG. 1), and the heating operation state in which the second compressor 21 sucks the refrigerant flowing from the outdoor heat exchanger 30 (see the solid line in the second four-way switching valve 22 in FIG. 1). When the predetermined defrosting start condition is satisfied while the heating operation is being executed in the second refrigerant circuit 20, the control unit 50 switches the connection state of the second four-way switching valve 22 from the heating operation state to the cooling operation state to execute the reverse cycle defrost operation. Then, when the predetermined defrosting end condition is satisfied, the control unit 50 returns the connection state of the second four-way switching valve 22 to the heating operation state again, and restores the heating operation in the second refrigerant circuit 20. Note that the predetermined defrosting start condition is not limited, but for example, if an outside air temperature sensor and a temperature sensor disposed below the outdoor heat exchanger 30 are installed (these temperature sensors can be shared with those in the first refrigerant circuit 10), defrosting start may be determined based on the detection temperature of these temperature sensors.

(1-2) Indoor Unit

In the first embodiment, as the plurality of indoor units, the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9 are provided. Each indoor unit is installed in an independent or continuous space, and can be a ceiling-embedded, ceiling-suspended, wall-mounted, or floor-mounted unit.

The first indoor unit 6 mainly includes a first indoor heat exchanger 61, a first indoor fan 62, and a first remote control device 63. The first indoor fan 62 forms an air flow obtained by taking in air of a target space for the first indoor unit 6 and returning the air to the target space again via the first indoor heat exchanger 61. The liquid refrigerant side of the first indoor heat exchanger 61 is connected to the first liquid-side shutoff valve 16 a of the outdoor unit 2 via the first liquid-side refrigerant connection pipe 65. The gas refrigerant side of the first indoor heat exchanger 61 is connected to the first gas-side shutoff valve 18 a of the outdoor unit 2 via the first gas-side refrigerant connection pipe 66. The first remote control device 63 is communicably connected to the control unit 50 and receives various operation commands from a user.

The second indoor unit 7 mainly includes a second indoor heat exchanger 71, a second indoor fan 72, and a second remote control device 73. The second indoor fan 72 forms an air flow obtained by taking in air of a target space for the second indoor unit 7 and returning the air to the target space again via the second indoor heat exchanger 71. The liquid refrigerant side of the second indoor heat exchanger 71 is connected to the second liquid-side shutoff valve 16 b of the outdoor unit 2 via the second liquid-side refrigerant connection pipe 75. The gas refrigerant side of the second indoor heat exchanger 71 is connected to the second gas-side shutoff valve 18 b of the outdoor unit 2 via the second gas-side refrigerant connection pipe 76. The second remote control device 73 is communicably connected to the control unit 50 and receives various operation commands from a user.

The third indoor unit 8 mainly includes a third indoor heat exchanger 81, a third indoor fan 82, and a third remote control device 83. The third indoor fan 82 forms an air flow obtained by taking in air of a target space for the third indoor unit 8 and returning the air to the target space again via the third indoor heat exchanger 81. The liquid refrigerant side of the third indoor heat exchanger 81 is connected to the third liquid-side shutoff valve 26 a of the outdoor unit 2 via the third liquid-side refrigerant connection pipe 85. The gas refrigerant side of the third indoor heat exchanger 81 is connected to the third gas-side shutoff valve 28 a of the outdoor unit 2 via the third gas-side refrigerant connection pipe 86. The third remote control device 83 is communicably connected to the control unit 50 and receives various operation commands from a user.

The fourth indoor unit 9 mainly includes a fourth indoor heat exchanger 91, a fourth indoor fan 92, and a fourth remote control device 93. The fourth indoor fan 92 forms an air flow obtained by taking in air of a target space for the fourth indoor unit 9 and returning the air to the target space again via the fourth indoor heat exchanger 91. The liquid refrigerant side of the fourth indoor heat exchanger 91 is connected to the fourth liquid-side shutoff valve 26 b of the outdoor unit 2 via the fourth liquid-side refrigerant connection pipe 95. The gas refrigerant side of the fourth indoor heat exchanger 91 is connected to the fourth gas-side shutoff valve 28 b of the outdoor unit 2 via the fourth gas-side refrigerant connection pipe 96. The fourth remote control device 93 is communicably connected to the control unit 50 and receives various operation commands from a user.

(1-3) Control Unit

The control unit 50 is a functional unit that controls operations of various devices constituting the air conditioning apparatus 1.

The control unit 50 is configured, for example, by communicably connecting an outdoor control unit (not shown) of the outdoor unit 2 via a transmission line (not shown) to an indoor control unit (not shown) provided in each of the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9. Each of the outdoor control unit and the indoor control unit is a unit including, for example, a microcomputer and a memory storing various programs for controlling the air conditioning apparatus 1, and the like, the programs being executable by the microcomputer. Note that for convenience, FIG. 1 draws the control unit 50 at a position away from the outdoor unit 2, the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9.

The control unit 50 is electrically connected to various devices such as the outdoor fan 30 a, the first compressor 11, the first four-way switching valve 12, the first expansion valve 15 a, the second expansion valve 15 b, the second compressor 21, the second four-way switching valve 22, the third expansion valve 25 a, and the fourth expansion valve 25 b. The control unit 50 is electrically connected to various sensors (not shown). As described above, the control unit 50 is communicably connected to the first remote control device 63, the second remote control device 73, the third remote control device 83, and the fourth remote control device 93 operated by a user of the air conditioning apparatus 1.

The control unit 50 controls the operation and stop of the air conditioning apparatus 1 and the operation of various devices constituting the air conditioning apparatus 1, based on measurement signals of various sensors, commands received from the first remote control device 63, the second remote control device 73, the third remote control device 83, and the fourth remote control device 93, and the like.

(2) Configuration of Outdoor Heat Exchanger

FIG. 2 is a schematic explanatory diagram of the outdoor heat exchanger 30.

The outdoor heat exchanger 30 includes a plurality of first heat transfer tubes 31, a plurality of second heat transfer tubes 32, a plurality of heat transfer fins 33, a first gas header 34, a second gas header 35, a first distributor 36, and a second distributor 37.

The plurality of heat transfer fins 33 is arranged in the plate thickness direction, which is the paper surface direction in FIG. 2. The plurality of first heat transfer tubes 31 and the plurality of second heat transfer tubes 32 penetrate. The heat transfer fins 33 are provided with a windward side heat transfer tube insertion part arranged up and down on the windward side in the air flow direction, and a downwind side heat transfer tube insertion part arranged up and down on the downwind side in the air flow direction.

The first gas header 34 is a header belonging to the first refrigerant circuit 10, and is provided on the gas side of the plurality of first heat transfer tubes 31 in the refrigerant flow path of the first refrigerant circuit 10. When the first refrigerant circuit 10 is in the cooling operation state, the first gas header 34 divides and supplies a gas refrigerant to a plurality of flow paths including the plurality of first heat transfer tubes 31. When the first refrigerant circuit 10 is in the heating operation state (see the refrigerant flow arrow in FIG. 2), the first gas header 34 merges the gas refrigerant that has flowed through the plurality of flow paths including the plurality of first heat transfer tubes 31.

The second gas header 35 is a header belonging to the second refrigerant circuit 20, and is provided on the gas side of the plurality of second heat transfer tubes 32 in the refrigerant flow path of the second refrigerant circuit 20. When the second refrigerant circuit 20 is in the cooling operation state, the second gas header 35 divides and supplies the gas refrigerant to a plurality of flow paths including the plurality of second heat transfer tubes 32. When the second refrigerant circuit 20 is in the heating operation state (see the refrigerant flow arrow in FIG. 2), the second gas header 35 merges the gas refrigerant that has flowed through the plurality of flow paths including the plurality of second heat transfer tubes 32.

The first distributor 36 is a distributor belonging to the first refrigerant circuit 10, and is provided on the liquid side of the plurality of first heat transfer tubes 31 in the refrigerant flow path of the first refrigerant circuit 10. When the first refrigerant circuit 10 is in the cooling operation state, the first distributor 36 merges the liquid refrigerant that has flowed through the plurality of flow paths including the plurality of first heat transfer tubes 31. When the first refrigerant circuit 10 is in the heating operation state (see the refrigerant flow arrow in FIG. 2), the first distributor 36 divides and supplies the liquid refrigerant to the plurality of flow paths including the plurality of first heat transfer tubes 31.

The second distributor 37 is a distributor belonging to the second refrigerant circuit 20, and is provided on the liquid side of the plurality of second heat transfer tubes 32 in the refrigerant flow path of the second refrigerant circuit 20. When the second refrigerant circuit 20 is in the cooling operation state, the second distributor 37 merges the liquid refrigerant that has flowed through the plurality of flow paths including the plurality of second heat transfer tubes 32. When the second refrigerant circuit 20 is in the heating operation state (see the refrigerant flow arrow in FIG. 2), the second distributor 37 divides and supplies the liquid refrigerant to the plurality of flow paths including the plurality of second heat transfer tubes 32.

The plurality of first heat transfer tubes 31 is heat transfer tubes belonging to the first refrigerant circuit 10, and the refrigerant flowing through the first refrigerant circuit 10 passes through the heat transfer tubes. The plurality of first heat transfer tubes 31 and the nearby heat transfer fins 33 are part of the outdoor heat exchanger 30, and constitute a first outdoor heat exchange unit 30 x belonging to the first refrigerant circuit 10. The refrigerant flowing through the first refrigerant circuit 10 is divided into and flows through a plurality of flow paths that is in parallel with each other and corresponds to the number of pipes connected to the first distributor 36 in the outdoor heat exchanger 30. Specifically, each flow path corresponding to the number of pipes connected to the first distributor 36 includes a branch part at a position closer to the gas side, while ends of the first heat transfer tubes 31 are connected to turn back via a U-shaped tube or the like. Note that in the first embodiment, each flow path corresponding to the number of pipes connected to the first distributor 36 is configured such that the number of first heat transfer tubes 31 on the liquid refrigerant side of the branch part, and the total number of first heat transfer tubes 31 divided on the gas refrigerant side of the branch part are equal to each other. In the first embodiment, the plurality of first heat transfer tubes 31 is arranged such that the first heat transfer tubes 31 do not overlap each other in the air flow direction.

The plurality of second heat transfer tubes 32 is heat transfer tubes belonging to the second refrigerant circuit 20, and the refrigerant flowing through the second refrigerant circuit 20 passes through the heat transfer tubes. The plurality of second heat transfer tubes 32 and the nearby heat transfer fins 33 are part of the outdoor heat exchanger 30, and constitute a second outdoor heat exchange unit 30 y belonging to the second refrigerant circuit 20. The refrigerant flowing through the second refrigerant circuit 20 is divided into and flows through a plurality of flow paths that is in parallel with each other and corresponds to the number of pipes connected to the second distributor 37 in the outdoor heat exchanger 30. Specifically, each flow path corresponding to the number of pipes connected to the second distributor 37 includes a branch part at a position closer to the gas side, while ends of the second heat transfer tube 32 are connected to turn back via a U-shaped tube or the like. Note that in the first embodiment, each flow path corresponding to the number of pipes connected to the second distributor 37 is configured such that the number of second heat transfer tubes 32 on the liquid refrigerant side of the branch part, and the total number of second heat transfer tubes 32 divided on the gas refrigerant side of the branch part are equal to each other. In the first embodiment, the plurality of second heat transfer tubes 32 is arranged such that the second heat transfer tubes 32 do not overlap each other in the air flow direction.

Note that as shown in FIG. 2, each flow path including the plurality of first heat transfer tubes 31 and corresponding to the number of pipes connected to the first distributor 36 is provided to intersect one of the flow paths including the plurality of second heat transfer tubes 32 and corresponding to the number of pipes connected to the second distributor 37 in a one-to-one correspondence. Specifically, in the outdoor heat exchanger 30 of the first embodiment, the plurality of flow paths including the plurality of first heat transfer tubes 31 and the plurality of flow paths including the plurality of second heat transfer tubes 32 are in a one-to-one correspondence, and are provided to intersect once within the width of the heat transfer fins 33 when viewed from the direction in which the first heat transfer tubes 31 and the second heat transfer tubes 32 extend. Note that in the air flow direction, the outdoor heat exchanger 30 of the first embodiment is configured such that at a place where the first heat transfer tubes 31 are arranged on the windward side, the second heat transfer tubes 32 are arranged on the downwind side, and at a place where the first heat transfer tubes 31 are arranged on the downwind side, the second heat transfer tubes 32 are arranged on the windward side. In the outdoor heat exchanger 30 of the first embodiment, a plurality of heat transfer tubes is arranged to overlap each other when viewed in the air flow direction.

In the first embodiment, the outdoor heat exchanger 30 and the outdoor fan 30 a are provided such that the direction of the refrigerant flow in the outdoor heat exchanger 30 is parallel to the direction of the air flow supplied from the outdoor fan 30 a to the outdoor heat exchanger 30, when the first refrigerant circuit 10 and the second refrigerant circuit 20 are both in the heating operation state as shown in the refrigerant flow of the heating operation state in FIG. 2.

(3) Characteristics of First Embodiment

The air conditioning apparatus 1 of the first embodiment includes the plurality of indoor units: the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9, and can process the heat load at the place where each indoor unit is disposed. Here, the air conditioning apparatus 1 processes the heat load at a plurality of places by using the plurality of refrigerant circuits independent of each other, the first refrigerant circuit 10 and the second refrigerant circuit 20. In this way, by processing the heat load at a plurality of places by using the plurality of refrigerant circuits, it is possible to keep the amount of refrigerant charged into one refrigerant circuit to a lower level than the case of using one refrigerant circuit, and specifically, to keep the amount of refrigerant charged into one refrigerant circuit to less than 1.84 kg.

Therefore, even if R32, which is a refrigerant classified by ISO817 as lower flammability (A2L), is charged into each of the first refrigerant circuit 10 and the second refrigerant circuit 20, it is possible to keep the amount of refrigerant leak to a low level when a refrigerant leak occurs in either the first refrigerant circuit 10 or the second refrigerant circuit 20. Therefore, even if a refrigerant leak occurs, it is possible to keep the combustion possibility to a low level.

In particular, in the air conditioning apparatus 1 of the first embodiment, a pipe with an outer diameter of 6.35 mm and an inner diameter of less than 4.75 mm is used in the first liquid-side refrigerant connection pipe 65, the second liquid-side refrigerant connection pipe 75, the third liquid-side refrigerant connection pipe 85, and the fourth liquid-side refrigerant connection pipe 95. Therefore, by keeping the inner diameter smaller than that of nibukan, which is widely distributed, the area of the flow path in a relatively high density place can be narrowed in the refrigerant circuit, and the amount of charged refrigerant can be kept to a low level.

Note that if the amount of refrigerant charged into the refrigerant circuit is kept to a low level in this way, the pressure loss is likely to occur in the refrigerant flowing through the refrigerant circuit during the refrigeration cycle. By using R32, which is a refrigerant that is less likely to cause the pressure loss than R410A or the like, such a decrease in efficiency caused by the pressure loss can be kept to a low level.

The heat transfer fins 33 of the outdoor heat exchanger 30 are attached such that the plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 penetrate. This allows the outdoor heat exchanger 30 to give and receive heat between the refrigerant flowing through the first refrigerant circuit 10 and the refrigerant flowing through the second refrigerant circuit 20, via the heat transfer fins 33 to which both the first heat transfer tubes 31 and the second heat transfer tubes 32 are attached. In particular, in the outdoor heat exchanger 30 of the first embodiment, for example, unlike the case where the heat transfer tubes are provided in only one row in the air flow direction, many places are secured where the plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 are disposed adjacent to each other. Specifically, in the outdoor heat exchanger 30 of the first embodiment, places where the first heat transfer tubes 31 and the second heat transfer tubes 32 are located within a distance range of equal to or less than twice the closest pitch of the plurality of first heat transfer tubes 31 arranged vertically are secured in half or more of the total number of plurality of first heat transfer tubes 31, enabling sufficient giving and receiving of heat between the refrigerant flowing through the first refrigerant circuit 10 and the refrigerant flowing through the second refrigerant circuit 20. This makes it possible to use the capacity of one refrigerant circuit by the other refrigerant circuit between the first refrigerant circuit 10 and the second refrigerant circuit 20. For example, when the cooling operation is executed in the first refrigerant circuit 10 and the heating operation is executed in the second refrigerant circuit 20 simultaneously by using the first indoor unit 6 and the second indoor unit 7 belonging to the first refrigerant circuit 10 for cooling a computer room or the like, it is possible to increase both the cooling capacity of the first refrigerant circuit 10 and the heating capacity of the second refrigerant circuit 20 by giving and receiving heat between the first refrigerant circuit 10 and the second refrigerant circuit 20 in the outdoor heat exchanger 30.

In the air conditioning apparatus 1 of the first embodiment, the outdoor heat exchanger 30 can be shared by the first refrigerant circuit 10 and the second refrigerant circuit 20. An air flow can be supplied to the outdoor heat exchanger 30 by using one outdoor fan 30 a. This allows the outdoor fan 30 a to be shared by the first refrigerant circuit 10 and the second refrigerant circuit 20.

Note that the outdoor heat exchanger 30 of the air conditioning apparatus 1 of the first embodiment is configured such that the number of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the number of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 arranged on the windward side are equal to each other. This makes it easier to balance the capacity of the first refrigerant circuit 10 and the second refrigerant circuit 20.

In the air conditioning apparatus 1 of the first embodiment, R32 is charged as a refrigerant into the first refrigerant circuit 10 and the second refrigerant circuit 20. The pressure loss when the R32 refrigerant passes through a heat exchanger used as an evaporator is kept to a lower level than conventionally used R410A. Therefore, by executing the heating operation in the first refrigerant circuit 10 or the second refrigerant circuit 20, even when the outdoor heat exchanger 30 functions as a refrigerant evaporator, it is possible to keep the temperature drop at a refrigerant outlet of the outdoor heat exchanger 30 to a low level. This makes it possible to suppress frost formation in the outdoor heat exchanger 30.

Therefore, for example, as shown in FIG. 3, consider a case where only the second refrigerant circuit 20 executes the heating operation and the operation of the first refrigerant circuit 10 is stopped. In this case, although frost tends to form in the hatched region A in the lower right part of the heat transfer fins 33 in FIG. 3, the use of R32 as a refrigerant can suppress the frost formation. By suppressing the frost formation in the region A, it is also possible to suppress the growth of frost to the hatched region B on the windward side of the region A. With this configuration, when the heating operation of the first refrigerant circuit 10 is also started, it is possible to avoid the situation where the heating capacity of the first refrigerant circuit 10 cannot be fully exhibited, and to suppress the occurrence of a situation in which the defrost operation needs to be performed when or immediately after the heating of the first refrigerant circuit 10 is started.

(4) Modifications of First Embodiment

(4-1) Modification A of First Embodiment

The first embodiment has described, by way of example, a case where R32, which is not a non-azeotropic mixed refrigerant, is used in the first refrigerant circuit 10 and the second refrigerant circuit 20.

In contrast, a non-azeotropic mixed refrigerant, which is a refrigerant classified by ISO817 as lower flammability (A2L), may be used in each of the first refrigerant circuit 10 and the second refrigerant circuit 20.

When a refrigerant cycle is performed in a refrigerant circuit into which the non-azeotropic mixed refrigerant is charged and the outdoor heat exchanger 30 functions as a refrigerant evaporator, the composition differs between the gas phase and the liquid phase of the refrigerant, and the temperature of the refrigerant on the downstream side of the refrigerant flowing through the outdoor heat exchanger 30 tends to rise. Therefore, for example, when the flow paths in the outdoor heat exchanger 30 include a plurality of heat transfer tubes belonging to the same refrigerant circuit, when the heat transfer tubes arranged on the windward side and the heat transfer tubes arranged on the downwind side are arranged in line in the air flow direction in the same flow path, in particular, it becomes difficult to sufficiently secure the temperature difference between the refrigerant flowing through the heat transfer tubes arranged on the downwind side and the air

In contrast, the outdoor heat exchanger 30 of the air conditioning apparatus 1 includes the plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20. The plurality of first heat transfer tubes 31 does not line up with each other in the air flow direction, and the plurality of second heat transfer tubes 32 does not line up with each other in the air flow direction. Specifically, the outdoor heat exchanger 30 includes one first heat transfer tube 31 and one second heat transfer tube 32 arranged in this order in the air flow direction, and one second heat transfer tube 32 and one first heat transfer tube 31 arranged in this order. Therefore, when only the first refrigerant circuit 10 is in operation or only the second refrigerant circuit 20 is in operation, it is possible to supply outside air whose temperature has not changed (there is no temperature change due to heat exchange in the heat transfer tubes on the upstream side) to any of the heat transfer tubes. This makes it possible to sufficiently secure the temperature difference between the refrigerant and the air and exchange heat even in the heat transfer tubes arranged on the downstream side in the air flow direction.

Note that as a refrigerant to be charged in the refrigerant circuit, when using one or more selected from the group consisting of R454A, R454B, and R454C, which are non-azeotropic mixed refrigerants classified by ISO817 as lower flammability (A2L), in particular, the increase in the refrigerant temperature on the downstream side of the refrigerant flowing through the outdoor heat exchanger 30 becomes remarkable. Therefore, when these refrigerants are used as the non-azeotropic mixed refrigerant, the above-described effects can be sufficiently obtained.

(4-2) Modification B of First Embodiment

The outdoor heat exchanger 30 in the first embodiment described above has been described by taking as an example the case where the number of first heat transfer tubes 31 is equal to the number of second heat transfer tubes 32, and the area ratio occupied by the plurality of first heat transfer tubes 31 is equal to the area ratio occupied by the second heat transfer tubes 32 in the heat transfer fins 33.

In contrast, for example, when the total processing load in one or the plurality of indoor units belonging to the first refrigerant circuit 10 differs from the total processing load in one or the plurality of indoor units belonging to the second refrigerant circuit 20, the ratio of the number of first heat transfer tubes 31 and the number of second heat transfer tubes 32 may be changed according to the processing load to change the ratio of the area ratio occupied by the plurality of first heat transfer tubes 31 and the area ratio occupied by the second heat transfer tubes 32 in the heat transfer fins 33.

(4-3) Modification C of First Embodiment

The application of the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9 in the first embodiment described above is not limited to air conditioning applications, nor is it limited to those commonly used in one type of application. These units may be used, for example, not only for air conditioning applications, but also for water heater applications and floor heating applications, and may be used in combination thereof.

(4-4) Modification D of First Embodiment

The air conditioning apparatus 1 in the first embodiment described above has been described by taking, as an example, the configuration in which in the outdoor heat exchanger 30, the refrigerant flow paths including the plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the refrigerant flow paths including the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 intersect in the middle of the outdoor heat exchanger 30.

In contrast, like an outdoor heat exchanger 130 shown in FIG. 4, the refrigerant flow paths including the plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the refrigerant flow paths including the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 may not intersect in the middle of the outdoor heat exchanger 30.

In this outdoor heat exchanger 130, the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 is arranged to be gathered on the windward lower side. The plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 is provided at positions on the downwind side of the plurality of second heat transfer tubes 32 and positions above the plurality of second heat transfer tubes 32.

Note that in this outdoor heat exchanger 130, the number of first heat transfer tubes 31 is larger than the number of second heat transfer tubes 32. Therefore, for example, the outdoor heat exchanger can be used for an air conditioning apparatus in which the processing load of the first refrigerant circuit 10 is larger than the processing load of the second refrigerant circuit 20.

(4-5) Modification E of First Embodiment

The air conditioning apparatus 1 of the first embodiment described above has been described by taking, as an example, the case where one outdoor heat exchanger 30 is shared by the first refrigerant circuit 10 and the second refrigerant circuit 20.

In contrast, as shown in FIG. 5, the outdoor unit 2 may separately include a first outdoor heat exchanger 230 x belonging to the first refrigerant circuit 10 and a second outdoor heat exchanger 230 y belonging to the second refrigerant circuit 20. Specifically, the heat transfer fins of the first outdoor heat exchanger 230 x and the heat transfer fins of the second outdoor heat exchanger 230 y may not be connected and may be used as separate members.

(5) Configuration of Air Conditioning Apparatus of Second Embodiment

An air conditioning apparatus of the second embodiment is almost the same as the air conditioning apparatus of the first embodiment, and differences will be mainly described below.

In the air conditioning apparatus of the second embodiment, pipes having pipe diameters according to the capacity of indoor heat exchangers 61, 71, 81, and 91 included in indoor units 6 to 9 to be connected are used for a first liquid-side refrigerant connection pipe 65, a second liquid-side refrigerant connection pipe 75, a third liquid-side refrigerant connection pipe 85, and a fourth liquid-side refrigerant connection pipe 95, respectively. Note that the pipe diameter of each liquid-side refrigerant connection pipe is smaller than the pipe diameter of paired gas-side refrigerant connection pipe for each indoor unit.

Pipes having pipe diameters according to the capacity of the indoor heat exchangers 61, 71, 81, and 91 included in the indoor units 6 to 9 to be connected are used for a first gas-side refrigerant connection pipe 66, a second gas-side refrigerant connection pipe 76, a third gas-side refrigerant connection pipe 86, and a fourth gas-side refrigerant connection pipe 96, respectively. In particular, in the second embodiment, the pipe diameter of the first gas-side refrigerant connection pipe 66 differs from the pipe diameter of the second gas-side refrigerant connection pipe 76. The pipe diameter of the first gas-side refrigerant connection pipe 66 is larger than the pipe diameter of the second gas-side refrigerant connection pipe 76. The pipe diameter of the third gas-side refrigerant connection pipe 86 differs from the pipe diameter of the fourth gas-side refrigerant connection pipe 96. The pipe diameter of the third gas-side refrigerant connection pipe 86 is larger than the pipe diameter of the fourth gas-side refrigerant connection pipe 96. In the second embodiment, the pipe diameter of the first gas-side refrigerant connection pipe 66 is larger than the pipe diameter of the third gas-side refrigerant connection pipe 86, the pipe diameter of the third gas-side refrigerant connection pipe 86 is larger than the pipe diameter of the second gas-side refrigerant connection pipe 76, and the pipe diameter of the second gas-side refrigerant connection pipe 76 is larger than the pipe diameter of the fourth gas-side refrigerant connection pipe 96.

(5-1) Outdoor Unit

In an outdoor unit 2 of the air conditioning apparatus 1 of the second embodiment, the capacity of a first compressor 11 of a first refrigerant circuit 10 and the capacity of a second compressor 21 of a second refrigerant circuit 20 are equal to each other. Here, equal capacity means that, for example, compressors of variable capacity have equal cylinder volume.

(5-2) Indoor Unit

The first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9 of the air conditioning apparatus 1 of the second embodiment are similar to respective indoor units of the first embodiment described above.

(5-3) Control Unit

A control unit 50 of the air conditioning apparatus 1 of the second embodiment is similar to the control unit of the first embodiment described above.

(6) Configuration of Outdoor Heat Exchanger

An outdoor heat exchanger 30 of the air conditioning apparatus 1 of the second embodiment is similar to the outdoor heat exchanger of the first embodiment described above.

(7) Arrangement Configuration of Shutoff Valves in Outdoor Unit

FIG. 6 is an external perspective view of the outdoor unit 2. FIG. 7 is an arrangement explanatory diagram of shutoff valves of the outdoor unit 2.

The outdoor unit 2 include an outdoor casing 40, which is a substantially rectangular enclosure that houses above-described components inside (outdoor heat exchanger 30, outdoor fan 30 a, first compressor 11, first four-way switching valve 12, first accumulator 13, first liquid pipe 14 a, second liquid pipe 14 b, first expansion valve 15 a, second expansion valve 15 b, first liquid-side shutoff valve 16 a, second liquid-side shutoff valve 16 b, first gas pipe 17 a, second gas pipe 17 b, first gas-side shutoff valve 18 a, second gas-side shutoff valve 18 b, second compressor 21, second four-way switching valve 22, second accumulator 23, third liquid pipe 24 a, fourth liquid pipe 24 b, third expansion valve 25 a, fourth expansion valve 25 b, third liquid-side shutoff valve 26 a, fourth liquid-side shutoff valve 26 b, third gas pipe 27 a, fourth gas pipe 27 b, third gas-side shutoff valve 28 a, and fourth gas-side shutoff valve 28 b).

The outdoor casing 40 is provided with a shutoff valve cover 41 that covers, from the side, the first liquid-side shutoff valve 16 a, the second liquid-side shutoff valve 16 b, the first gas-side shutoff valve 18 a, the second gas-side shutoff valve 18 b, the third liquid-side shutoff valve 26 a, the fourth liquid-side shutoff valve 26 b, the third gas-side shutoff valve 28 a, and the fourth gas-side shutoff valve 28 b. The rear of the shutoff valve cover 41 is open to pass each connection pipe to be connected to each shutoff valve. Here, the first liquid-side refrigerant connection pipe 65 is connected to the first liquid-side shutoff valve 16 a. The second liquid-side refrigerant connection pipe 75 is connected to the second liquid-side shutoff valve 16 b. The first gas-side refrigerant connection pipe 66 is connected to the first gas-side shutoff valve 18 a. The second gas-side refrigerant connection pipe 76 is connected to the second gas-side shutoff valve 18 b. The third liquid-side refrigerant connection pipe 85 is connected to the third liquid-side shutoff valve 26 a. The fourth liquid-side refrigerant connection pipe 95 is connected to the fourth liquid-side shutoff valve 26 b. The third gas-side refrigerant connection pipe 86 is connected to the third gas-side shutoff valve 28 a. The fourth gas-side refrigerant connection pipe 96 is connected to the fourth gas-side shutoff valve 28 b.

The first liquid-side shutoff valve 16 a, the second liquid-side shutoff valve 16 b, the first gas-side shutoff valve 18 a, the second gas-side shutoff valve 18 b, the third liquid-side shutoff valve 26 a, the fourth liquid-side shutoff valve 26 b, the third gas-side shutoff valve 28 a, and the fourth gas-side shutoff valve 28 b are fixed to a shutoff valve support plate 42, which includes sheet metal fixed to a bottom plate of the outdoor casing 40. Specifically, the valves are arranged in the order of, from the bottom, a pair of the first liquid-side shutoff valve 16 a and the first gas-side shutoff valve 18 a, a pair of the second liquid-side shutoff valve 16 b and the second gas-side shutoff valve 18 b, a pair of the third liquid-side shutoff valve 26 a and the third gas-side shutoff valve 28 a, and a pair of the fourth liquid-side shutoff valve 26 b and the fourth gas-side shutoff valve 28 b. In this way, the gas-side refrigerant connection pipes connected to respective gas-side shutoff valves are arranged such that the pipe diameter gradually decreases in order from the bottom.

Here, the first liquid-side refrigerant connection pipe 65, the second liquid-side refrigerant connection pipe 75, the third liquid-side refrigerant connection pipe 85, the fourth liquid-side refrigerant connection pipe 95, the first gas-side refrigerant connection pipe 66, the second gas-side refrigerant connection pipe 76, the third gas-side refrigerant connection pipe 86, and the fourth gas-side refrigerant connection pipe 96 all extend backward from respective shutoff valves and then are bent upward at curved portions 66R, 76R, 86R, and 96R of respective refrigerant connection pipes (only gas-side refrigerant connection pipe side is shown by the broken line in FIG. 7), are combined into one, and extend further upward.

(8) Characteristics of Second Embodiment

The air conditioning apparatus 1 of the second embodiment includes the plurality of indoor units: the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9, and can process the heat load at the place where each indoor unit is disposed. Here, the air conditioning apparatus 1 processes the heat load at a plurality of places by using the plurality of refrigerant circuits independent of each other, the first refrigerant circuit 10 and the second refrigerant circuit 20. In this way, by processing the heat load at a plurality of places by using the plurality of refrigerant circuits, it is possible to keep the amount of refrigerant charged into one refrigerant circuit to a lower level than the case of using one refrigerant circuit, and specifically, to keep the amount of refrigerant charged into one refrigerant circuit to less than 1.84 kg.

Therefore, even if R32, which is a refrigerant classified by ISO817 as lower flammability (A2L), is charged into each of the first refrigerant circuit 10 and the second refrigerant circuit 20, it is possible to keep the amount of refrigerant leak to a low level when a refrigerant leak occurs in either the first refrigerant circuit 10 or the second refrigerant circuit 20. Therefore, even if a refrigerant leak occurs, it is possible to keep the combustion possibility to a low level.

The air conditioning apparatus 1 of the second embodiment includes four gas-side refrigerant connection pipes: the first gas-side refrigerant connection pipe 66, the second gas-side refrigerant connection pipe 76, the third gas-side refrigerant connection pipe 86, and the fourth gas-side refrigerant connection pipe 96. Out of these pipes, the two high-ranking pipes having a large pipe diameter, the first gas-side refrigerant connection pipe 66 and the third gas-side refrigerant connection pipe 86 belong to different refrigerant circuits. Specifically, the first gas-side refrigerant connection pipe 66 belongs to the first refrigerant circuit 10, and the third gas-side refrigerant connection pipe 86 belongs to the second refrigerant circuit 20. This makes it possible to suppress an imbalance of capacity between the refrigerant circuits and to make the shortage or excess of capacity difficult to occur in each indoor unit.

Out of the plurality of gas-side refrigerant connection pipes, the two low-ranking pipes having a small pipe diameter, the second gas-side refrigerant connection pipe 76 and the fourth gas-side refrigerant connection pipe 96 also belong to different refrigerant circuits. Specifically, the second gas-side refrigerant connection pipe 76 belongs to the first refrigerant circuit 10, and the fourth gas-side refrigerant connection pipe 96 belongs to the second refrigerant circuit 20. This makes it possible to further suppress the imbalance of capacity between the refrigerant circuits.

In particular, in the second embodiment, since the first compressor 11 of the first refrigerant circuit 10 and the second compressor 21 of the second refrigerant circuit 20 have the same capacity, it is possible to balance the capacity of respective refrigerant circuits, by providing different refrigerant circuits with the two high-ranking pipes having a large pipe diameter out of the plurality of gas-side refrigerant connection pipes, and by providing different refrigerant circuits with the two low-ranking pipes having a small pipe diameter out of the plurality of gas-side refrigerant connection pipes, as described above.

In the outdoor unit 2, the first gas-side shutoff valve 18 a to which the first gas-side refrigerant connection pipe 66 belonging to the first refrigerant circuit 10 is connected, the third gas-side shutoff valve 28 a to which the third gas-side refrigerant connection pipe 86 belonging to the second refrigerant circuit 20 is connected, the second gas-side shutoff valve 18 b to which the second gas-side refrigerant connection pipe 76 belonging to the first refrigerant circuit 10 is connected, and the fourth gas-side shutoff valve 28 b to which the fourth gas-side refrigerant connection pipe 96 belonging to the second refrigerant circuit 20 is connected are arranged in order from the bottom. Therefore, the gas-side shutoff valves belonging to the first refrigerant circuit 10 and the gas-side shutoff valves belonging to the second refrigerant circuit 20 can be arranged at staggered height positions. This makes it possible to avoid a structure in which only the gas-side shutoff valves belonging to either one of the refrigerant circuits are arranged together upward or downward, to equalize the head difference between the refrigerant circuits, and to equalize the capacity.

The refrigerant connection pipes extending from the outdoor unit 2 (first liquid-side refrigerant connection pipe 65, first gas-side refrigerant connection pipe 66, second liquid-side refrigerant connection pipe 75, second gas-side refrigerant connection pipe 76, third liquid-side refrigerant connection pipe 85, third gas-side refrigerant connection pipe 86, fourth liquid-side refrigerant connection pipe 95, and fourth gas-side refrigerant connection pipe 96) are all provided to extend upward from the outdoor casing 40. This makes it possible to lead each refrigerant connection pipe extending from the outdoor unit 2 to a higher position in the room or ceiling space, which is the air conditioning target space. This eliminates the need for installing each refrigerant connection pipe upward, such as along a wall surface of the room to the indoor units (first indoor unit 6, second indoor unit 7, third indoor unit 8, fourth indoor unit 9), and makes it possible to make each refrigerant connection pipe inconspicuous indoors.

In general, as the pipe diameter increases, the bending radius required for bending while suppressing damage tends to be large. In contrast, in the outdoor unit 2 of the second embodiment, the first gas-side shutoff valve 18 a to which the first gas-side refrigerant connection pipe 66 having the largest pipe diameter is connected, the third gas-side shutoff valve 28 a to which the third gas-side refrigerant connection pipe 86 having the second largest pipe diameter is connected, the second gas-side shutoff valve 18 b to which the second gas-side refrigerant connection pipe 76 having the third largest pipe diameter is connected, and the fourth gas-side shutoff valve 28 b to which the fourth gas-side refrigerant connection pipe 96 having the smallest pipe diameter is connected are arranged in order from the bottom. Therefore, the gas-side refrigerant connection pipe having a relatively large pipe diameter can secure a wider space for the curved portion, and can secure a large bending radius. This makes it possible to improve the workability when each gas-side refrigerant connection pipe is bent and connected to the gas-side shutoff valve.

The heat transfer fins 33 of the outdoor heat exchanger 30 are attached such that the plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 penetrate. This allows the outdoor heat exchanger 30 to give and receive heat between the refrigerant flowing through the first refrigerant circuit 10 and the refrigerant flowing through the second refrigerant circuit 20, via the heat transfer fins 33 to which both the first heat transfer tubes 31 and the second heat transfer tubes 32 are attached. This makes it possible to use the capacity of one refrigerant circuit by the other refrigerant circuit between the first refrigerant circuit 10 and the second refrigerant circuit 20. For example, when the cooling operation is executed in the first refrigerant circuit 10 and the heating operation is executed in the second refrigerant circuit 20 simultaneously by using the first indoor unit 6 and the second indoor unit 7 belonging to the first refrigerant circuit 10 for cooling a computer room or the like, it is possible to increase both the cooling capacity of the first refrigerant circuit 10 and the heating capacity of the second refrigerant circuit 20 by giving and receiving heat between the first refrigerant circuit 10 and the second refrigerant circuit 20 in the outdoor heat exchanger 30.

(9) Modifications of Second Embodiment

(9-1) Modification A of Second Embodiment

The second embodiment has described, as an example, the case where R32, which is not a non-azeotropic mixed refrigerant, is used in the first refrigerant circuit 10 and the second refrigerant circuit 20.

In contrast, a non-azeotropic mixed refrigerant, which is a refrigerant classified by ISO817 as lower flammability (A2L), may be used with the amount of charged refrigerant of less than 1.84 kg in each of the first refrigerant circuit 10 and the second refrigerant circuit 20. Examples of the non-azeotropic mixed refrigerant include R454A, R454B, and R454C.

(9-2) Modification B of Second Embodiment

The second embodiment described above has described, as an example, the case where the first gas-side shutoff valve 18 a to which the first gas-side refrigerant connection pipe 66 belonging to the first refrigerant circuit 10 is connected, the third gas-side shutoff valve 28 a to which the third gas-side refrigerant connection pipe 86 belonging to the second refrigerant circuit 20 is connected, the second gas-side shutoff valve 18 b to which the second gas-side refrigerant connection pipe 76 belonging to the first refrigerant circuit 10 is connected, and the fourth gas-side shutoff valve 28 b to which the fourth gas-side refrigerant connection pipe 96 belonging to the second refrigerant circuit 20 is connected are arranged in order from the bottom.

In contrast, for example, as shown in FIG. 8, the first gas-side shutoff valve 18 a to which the first gas-side refrigerant connection pipe 66 belonging to the first refrigerant circuit 10 is connected, the third gas-side shutoff valve 28 a to which the third gas-side refrigerant connection pipe 86 belonging to the second refrigerant circuit 20 is connected, the fourth gas-side shutoff valve 28 b to which the fourth gas-side refrigerant connection pipe 96 belonging to the second refrigerant circuit 20 is connected, and the second gas-side shutoff valve 18 b to which the second gas-side refrigerant connection pipe 76 belonging to the first refrigerant circuit 10 is connected may be arranged in order from the bottom. Here, the first gas-side shutoff valve 18 a, the third gas-side shutoff valve 28 a, the fourth gas-side shutoff valve 28 b, and the second gas-side shutoff valve 18 b may be fixed to the shutoff valve support plate 42, which is one sheet metal.

In this case, for example, when the cooling operation is executed in the first refrigerant circuit 10 and the heating operation is executed in the second refrigerant circuit 20 simultaneously, or when the heating operation is executed in the first refrigerant circuit 10 and the cooling operation is executed in the second refrigerant circuit 20 simultaneously, it is possible to suppress the giving and receiving of air between the first gas-side shutoff valve 18 a, the third gas-side shutoff valve 28 a, the fourth gas-side shutoff valve 28 b, and the second gas-side shutoff valve 18 b, and heat via the shutoff valve support plate 42, and to improve the efficiency.

For example, the case where the cooling operation is executed in the first refrigerant circuit 10 and the heating operation is executed in the second refrigerant circuit 20 will be described. To begin with, the temperature of the second gas-side shutoff valve 18 b is decreased by the refrigerant whose temperature has decreased due to evaporation in the indoor heat exchanger 71. The temperatures of the third gas-side shutoff valve 28 a and the fourth gas-side shutoff valve 28 b are increased by the high-temperature refrigerant discharged from the second compressor 21. The low-temperature second gas-side shutoff valve 18 b is not arranged at a position between the high-temperature third gas-side shutoff valve 28 a and the high-temperature fourth gas-side shutoff valve 28 b, but is arranged at a position far above the high-temperature third gas-side shutoff valve 28 a and near the high-temperature fourth gas-side shutoff valve 28 b only. This makes it possible to prevent a bad influence of a decrease in the temperature of both the third gas-side shutoff valve 28 a and the fourth gas-side shutoff valve 28 b by the low-temperature second gas-side shutoff valve 18 b, and to limit the influence of the low-temperature second gas-side shutoff valve 18 b to only the third gas-side shutoff valve 28 a. This makes it possible to deliver the refrigerant discharged from the second compressor 21 during the heating operation to the third indoor heat exchanger 81 while keeping the temperature high.

(9-3) Modification C of Second Embodiment

The second embodiment has described, as an example, the case where the air conditioning apparatus 1 of the second embodiment described above is provided with two refrigerant circuits independent of each other and two indoor units are connected to each refrigerant circuit.

However, the number of refrigerant circuits independent of each other included in the air conditioning apparatus is not limited to two, and may be three or more.

The number of indoor units per one refrigerant circuit is not limited to two, and may be one, or three or more.

The type of pipe diameter of the gas refrigerant connection pipe included in one refrigerant circuit is not limited to two, and may be three or more.

(9-4) Modification D of Second Embodiment

The application of the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9 in the second embodiment described above is not limited to air conditioning applications, nor is it limited to those commonly used in one type of application. These units may be used, for example, not only for air conditioning applications, but also for water heater applications and floor heating applications, and may be used in combination thereof.

(10) Configuration of Air Conditioning Apparatus of Third Embodiment

An air conditioning apparatus of the third embodiment is almost the same as the air conditioning apparatus of the first embodiment, and differences will be mainly described below.

In the air conditioning apparatus of the third embodiment, pipes having pipe diameters according to the capacity of indoor heat exchangers 61, 71, 81, and 91 included in indoor units 6 to 9 to be connected are used for a first liquid-side refrigerant connection pipe 65, a second liquid-side refrigerant connection pipe 75, a third liquid-side refrigerant connection pipe 85, and a fourth liquid-side refrigerant connection pipe 95, respectively. Note that the pipe diameter of each liquid-side refrigerant connection pipe is smaller than the pipe diameter of paired gas-side refrigerant connection pipe for each indoor unit.

Pipes having pipe diameters according to the capacity of the indoor heat exchangers 61, 71, 81, and 91 included in the indoor units 6 to 9 to be connected are used for a first gas-side refrigerant connection pipe 66, a second gas-side refrigerant connection pipe 76, a third gas-side refrigerant connection pipe 86, and a fourth gas-side refrigerant connection pipe 96, respectively. In particular, in the third embodiment, the pipe diameter of the first gas-side refrigerant connection pipe 66 differs from the pipe diameter of the second gas-side refrigerant connection pipe 76. The pipe diameter of the first gas-side refrigerant connection pipe 66 is larger than the pipe diameter of the second gas-side refrigerant connection pipe 76. The pipe diameter of the third gas-side refrigerant connection pipe 86 differs from the pipe diameter of the fourth gas-side refrigerant connection pipe 96. The pipe diameter of the third gas-side refrigerant connection pipe 86 is larger than the pipe diameter of the fourth gas-side refrigerant connection pipe 96. In the third embodiment, the pipe diameter of the first gas-side refrigerant connection pipe 66 is larger than the pipe diameter of the third gas-side refrigerant connection pipe 86, the pipe diameter of the third gas-side refrigerant connection pipe 86 is larger than the pipe diameter of the second gas-side refrigerant connection pipe 76, and the pipe diameter of the second gas-side refrigerant connection pipe 76 is larger than the pipe diameter of the fourth gas-side refrigerant connection pipe 96.

(10-1) Outdoor Unit

In an outdoor unit 2 of the air conditioning apparatus 1 of the third embodiment, the capacity of a first compressor 11 of a first refrigerant circuit 10 and the capacity of a second compressor 21 of a second refrigerant circuit 20 differ from each other. Specifically, in the third embodiment, the capacity of the first compressor 11 is larger than the capacity of the second compressor 21. Note that the capacity of a compressor, for example, the capacity of a compressor of variable capacity can be obtained by comparison of the cylinder volume.

(10-2) Indoor Unit

The first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9 of the air conditioning apparatus 1 of the third embodiment are similar to respective indoor units of the first embodiment described above.

(10-3) Control Unit

A control unit 50 of the air conditioning apparatus 1 of the third embodiment is similar to the control unit of the first embodiment described above. Note that in the third embodiment, when instructions of cooling operation or heating operation are received from a first remote control device 63 or a second remote control device 73 corresponding to the first refrigerant circuit 10, and when instructions of heating operation or cooling operation are received from a third remote control device 83 or a fourth remote control device 93 corresponding to the second refrigerant circuit 20, the control unit 50 executes the cooling operation and the heating operation simultaneously in the first refrigerant circuit 10 and the second refrigerant circuit 20.

(11) Configuration of Outdoor Heat Exchanger

An outdoor heat exchanger 30 of the air conditioning apparatus 1 of the third embodiment is almost similar to the outdoor heat exchanger of the first embodiment described above, but unlike the first embodiment, part of the plurality of first heat transfer tubes 31 is arranged such that the first heat transfer tubes 31 overlap each other in the air flow direction near an upper end of the outdoor heat exchanger 30 in the third embodiment.

As shown in FIG. 9, the third embodiment has a configuration in which the number of plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 is larger than the number of plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20.

As shown in FIG. 9, the third embodiment has a configuration in which the number of flow paths including the plurality of first heat transfer tubes 31 and corresponding to the number of pipes connected to a first distributor 36 is larger than the number of flow paths including the plurality of second heat transfer tubes 32 and corresponding to the number of pipes connected to a second distributor 37. In a portion near the upper end of the outdoor heat exchanger 30, two flow paths including the plurality of first heat transfer tubes 31 each include a windward heat transfer tube and a downwind heat transfer tube. Below the portion near the upper end of the outdoor heat exchanger 30, the plurality of flow paths including the plurality of first heat transfer tubes 31 and the plurality of flow paths including the plurality of second heat transfer tubes 32 are in a one-to-one correspondence, and are provided to intersect once in a width range of the heat transfer fins 33 when viewed from the direction in which the first heat transfer tubes 31 and the second heat transfer tubes 32 extend. Note that the outdoor heat exchanger 30 of the third embodiment has a configuration in which, below the portion near the upper end of the outdoor heat exchanger 30, in the air flow direction, at a place where the first heat transfer tubes 31 are arranged on the windward side, the second heat transfer tubes 32 are arranged on the downwind side, and at a place where the first heat transfer tubes 31 are arranged on the downwind side, the second heat transfer tubes 32 are arranged on the windward side. In the outdoor heat exchanger 30 of the third embodiment, a plurality of heat transfer tubes is arranged to overlap each other when viewed in the air flow direction.

In the third embodiment, the outdoor heat exchanger 30 and an outdoor fan 30 a are provided such that the direction of the refrigerant flow in the outdoor heat exchanger 30 is parallel to the direction of the air flow supplied from the outdoor fan 30 a to the outdoor heat exchanger 30, when the first refrigerant circuit 10 and the second refrigerant circuit 20 are both in the heating operation state as shown in the refrigerant flow of the heating operation state in FIG. 9.

(12) Characteristics of Third Embodiment

The air conditioning apparatus 1 of the third embodiment includes the plurality of indoor units: the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9, and can process the heat load at the place where each indoor unit is disposed. Here, the air conditioning apparatus 1 processes the heat load at a plurality of places by using the plurality of refrigerant circuits independent of each other, the first refrigerant circuit 10 and the second refrigerant circuit 20. In this way, by processing the heat load at a plurality of places by using the plurality of refrigerant circuits, it is possible to keep the amount of refrigerant charged into one refrigerant circuit to a lower level than the case of using one refrigerant circuit, and specifically, to keep the amount of refrigerant charged into one refrigerant circuit to less than 1.84 kg.

Therefore, even if R32, which is a refrigerant classified by ISO817 as lower flammability (A2L), is charged into each of the first refrigerant circuit 10 and the second refrigerant circuit 20, it is possible to keep the amount of refrigerant leak to a low level when a refrigerant leak occurs in either the first refrigerant circuit 10 or the second refrigerant circuit 20. Therefore, even if a refrigerant leak occurs, it is possible to keep the combustion possibility to a low level.

In the air conditioning apparatus 1 of the third embodiment, in the first refrigerant circuit 10 including the first compressor 11, which is a compressor having large capacity, the first gas-side refrigerant connection pipe 66 having the largest pipe diameter is used, out of the plurality of gas-side refrigerant connection pipes included in the air conditioning apparatus 1. This makes it possible to assign the gas-side refrigerant connection pipe having a pipe diameter commensurate with the capacity of the compressor of each refrigerant circuit, and to inhibit the pipe size from becoming too large or too small, thereby making it possible to improve the operating efficiency of each refrigerant circuit. Furthermore, in the air conditioning apparatus 1 of the third embodiment, in the second refrigerant circuit 20 including the second compressor 21, which is a compressor having small capacity, the fourth gas-side refrigerant connection pipe 96 having the smallest pipe diameter is used, out of the plurality of gas-side refrigerant connection pipes included in the air conditioning apparatus 1. This also improves the operating efficiency of the air conditioning apparatus 1.

Furthermore, in the air conditioning apparatus 1 of the third embodiment, the pipe diameter of the first gas-side refrigerant connection pipe 66 of the first refrigerant circuit 10 is larger than the pipe diameter of the third gas-side refrigerant connection pipe 86 of the second refrigerant circuit 20, and the pipe diameter of the second gas-side refrigerant connection pipe 76 of the first refrigerant circuit 10 is larger than the pipe diameter of the fourth gas-side refrigerant connection pipe 96 of the second refrigerant circuit 20. That is, the sum of the pipe diameters of the plurality of gas-side refrigerant connection pipes included in the first refrigerant circuit 10 is larger than the sum of the pipe diameters of the plurality of gas-side refrigerant connection pipes included in the second refrigerant circuit 20. This allows the air conditioning apparatus 1 to make the sum of the pipe diameters of the plurality of gas-side refrigerant connection pipes included in the first refrigerant circuit 10 including the first compressor 11, which is a compressor having large capacity, larger than the sum of the pipe diameters of the plurality of gas-side refrigerant connection pipes included in the first refrigerant circuit 10 including the second compressor 21, which is a compressor having small capacity. This also makes it possible to assign the sum of the pipe diameters commensurate with the capacity of the compressor of each refrigerant circuit, and to inhibit the total pipe size from becoming too large or too small, thereby improving the operating efficiency of the air conditioning apparatus 1.

The outdoor heat exchanger 30 of the air conditioning apparatus 1 has a configuration in which the number of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 including the first compressor 11, which is a compressor having large capacity, is larger than the number of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 including the second compressor 21, which is a compressor having small capacity. This makes it possible to distribute the capacity of the outdoor heat exchanger 30 according to the capacity of the compressor in each refrigerant circuit.

The heat transfer fins 33 of the outdoor heat exchanger 30 are attached such that the plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 penetrate. This allows the outdoor heat exchanger 30 to give and receive heat between the refrigerant flowing through the first refrigerant circuit 10 and the refrigerant flowing through the second refrigerant circuit 20, via the heat transfer fins 33 to which both the first heat transfer tubes 31 and the second heat transfer tubes 32 are attached. In particular, in the outdoor heat exchanger 30 of the third embodiment, for example, unlike the case where the heat transfer tubes are provided in only one row in the air flow direction, many places are secured where the plurality of first heat transfer tubes 31 belonging to the first refrigerant circuit 10 and the plurality of second heat transfer tubes 32 belonging to the second refrigerant circuit 20 are arranged adjacent to each other. Specifically, in the outdoor heat exchanger 30 of the third embodiment, below the portion near the upper end of the outdoor heat exchanger 30, places where the first heat transfer tubes 31 and the second heat transfer tubes 32 are located within a distance range of equal to or less than twice the closest pitch of the plurality of first heat transfer tubes 31 arranged vertically are secured in half or more of the total number of plurality of first heat transfer tubes 31, enabling sufficient giving and receiving of heat between the refrigerant flowing through the first refrigerant circuit 10 and the refrigerant flowing through the second refrigerant circuit 20. This makes it possible to use the capacity of one refrigerant circuit by the other refrigerant circuit between the first refrigerant circuit 10 and the second refrigerant circuit 20. For example, when the cooling operation is executed in the first refrigerant circuit 10 and the heating operation is executed in the second refrigerant circuit 20 simultaneously by using the first indoor unit 6 and the second indoor unit 7 belonging to the first refrigerant circuit 10 for cooling a computer room or the like, it is possible to increase both the cooling capacity of the first refrigerant circuit 10 and the heating capacity of the second refrigerant circuit 20 by giving and receiving heat between the first refrigerant circuit 10 and the second refrigerant circuit 20 in the outdoor heat exchanger 30.

(13) Modifications of Third Embodiment

(13-1) Modification A of Third Embodiment

The third embodiment has described, as an example, the case where R32, which is not a non-azeotropic mixed refrigerant, is used in the first refrigerant circuit 10 and the second refrigerant circuit 20.

In contrast, a non-azeotropic mixed refrigerant, which is a refrigerant classified by ISO817 as lower flammability (A2L), may be used with the amount of charged refrigerant of less than 1.84 kg in each of the first refrigerant circuit 10 and the second refrigerant circuit 20. Examples of the non-azeotropic mixed refrigerant include R454A, R454B, and R454C.

(13-2) Modification B of Third Embodiment

The third embodiment described above has described, as an example, the case where the pipe diameters of the gas-side refrigerant connection pipes of the air conditioning apparatus 1 differ from each other.

In contrast, in the air conditioning apparatus 1, the plurality of gas-side refrigerant connection pipes included in the first refrigerant circuit 10 may all have the same pipe diameter, and the plurality of gas-side refrigerant connection pipes included in the second refrigerant circuit 20 may all have the same pipe diameter.

Furthermore, all the plurality of gas-side refrigerant connection pipes included in the air conditioning apparatus 1 may have the same pipe diameter. Note that in the configuration of this case, the number of gas-side refrigerant connection pipes included in the refrigerant circuit including the compressor having the maximum capacity is larger than the number of gas-side refrigerant connection pipes included in the other refrigerant circuit.

(13-3) Modification C of Third Embodiment

The air conditioning apparatus 1 of the third embodiment described above has been described by taking the case, as an example, where, when instructions of cooling operation or heating operation are received from the first remote control device 63 or the second remote control device 73 corresponding to the first refrigerant circuit 10, and when instructions of heating operation or cooling operation are received from the third remote control device 83 or the fourth remote control device 93 corresponding to the second refrigerant circuit 20, the control unit 50 executes the cooling operation and the heating operation simultaneously in the first refrigerant circuit 10 and the second refrigerant circuit 20.

In contrast, the condition for simultaneously executing the cooling operation and the heating operation in the first refrigerant circuit 10 and the second refrigerant circuit 20 is not limited to such setting by the remote control devices.

For example, the control unit 50 may store a predetermined load reference condition in a memory or the like in advance, and determine whether the load to be processed by the indoor unit belonging to the refrigerant circuit in operation exceeds the predetermined load reference condition when only one of the first refrigerant circuit 10 and the second refrigerant circuit 20 is in operation. When it is determined that the load exceeds the predetermined load reference condition, the control unit 50 may start the operation of the refrigerant circuit out of operation differently from the refrigerant circuit in operation, thereby causing the refrigerant circuit out of operation to support the load processing on the refrigerant circuit side in operation. Specifically, for example, when the heating operation is executed in the first refrigerant circuit 10 and the load processed by the first indoor unit 6 or the second indoor unit 7 exceeds the predetermined load reference condition, the cooling operation may be started in the second refrigerant circuit 20 out of operation, thereby increasing the evaporation efficiency of the refrigerant flowing through the first refrigerant circuit 10 of the outdoor heat exchanger 30.

(13-4) Modification D of Third Embodiment

The air conditioning apparatus 1 of the third embodiment described above has been described by taking, as an example, the case where two refrigerant circuits independent of each other are provided and two indoor units are connected to each refrigerant circuit.

However, the number of refrigerant circuits independent of each other included in the air conditioning apparatus is not limited to two, and may be three or more.

The number of indoor units per one refrigerant circuit is not limited to two, and may be one, or three or more.

The type of pipe diameter of the gas refrigerant connection pipe included in one refrigerant circuit is not limited to two, and may be three or more.

(13-5) Modification E of Third Embodiment

The application of the first indoor unit 6, the second indoor unit 7, the third indoor unit 8, and the fourth indoor unit 9 in the third embodiment described above is not limited to air conditioning applications, nor is it limited to those commonly used in one type of application. These units may be used, for example, not only for air conditioning applications, but also for water heater applications and floor heating applications, and may be used in combination thereof.

(Note)

Note that in the heat source-side heat exchanger, at least two or more of the plurality of second heat transfer tubes may be arranged on a downwind side of any one of the plurality of first heat transfer tubes, and at least two or more of the plurality of first heat transfer tubes may be arranged on a windward side of any one of the plurality of second heat transfer tubes. In the heat source-side heat exchanger, there may be no second heat transfer tube arranged on a windward side of the plurality of first heat transfer tubes.

Note that the first heat transfer tubes and the second heat transfer tubes may be arranged to overlap each other or may be arranged not to overlap each other in the air flow direction.

Note that half or more of the plurality of first heat transfer tubes may be arranged on a windward side of any one of the plurality of second heat transfer tubes.

Note that the heat source-side unit may be commonly used in the plurality of refrigerant circuits. The heat source-side unit commonly used in the plurality of refrigerant circuits can be the heat source-side unit including part of each of the refrigerant circuits independent of each other. For example, the heat source-side unit may include each heat source-side heat exchanger belonging to each refrigerant circuit and be unitized, or may include a compressor belonging to each refrigerant circuit and be unitized. Here, when the heat source-side unit includes each heat source-side heat exchanger belonging to each refrigerant circuit and is unitized, each heat source-side heat exchanger belonging to each refrigerant circuit may be a separate heat exchanger having separate heat transfer fin, or the heat source-side heat exchanger belonging to each refrigerant circuit may include a common heat transfer fin.

Note that when the plurality of refrigerant circuits of the refrigerant cycle system includes a plurality of pipes having a pipe diameter smaller than the pipe diameter of the “two high-ranking pipes having a large pipe diameter”, the plurality of pipes having a small pipe diameter may be separated into two or more refrigerant circuits.

Note that out of the plurality of gas refrigerant connection pipes, when a plurality of “two high-ranking pipes having a large pipe diameter” that have the second largest pipe diameter is present, an arbitrary one of the pipes can correspond to the “two high-ranking pipes having a large pipe diameter”.

Note that out of the plurality of gas refrigerant connection pipes, when a plurality of “two low-ranking pipes having a small pipe diameter” that has the second smallest pipe diameter is present, an arbitrary one of the pipes can correspond to the “two low-ranking pipes having a small pipe diameter”.

Note that the shutoff valve of the gas refrigerant connection pipe having the minimum pipe diameter and included in the second refrigerant circuit, the shutoff valve of the gas refrigerant connection pipe having the minimum pipe diameter and included in the first refrigerant circuit, the shutoff valve of the gas refrigerant connection pipe having the maximum pipe diameter and included in the second refrigerant circuit, and the shutoff valve of the gas refrigerant connection pipe having the maximum pipe diameter and included in the first refrigerant circuit may be arranged in line in order from the top without any other shutoff valve that lies between the shutoff valves, or may be arranged in line in order from the top while another shutoff valve lies between the shutoff valves.

Note that the shutoff valve of the gas refrigerant connection pipe having the minimum pipe diameter and included in the first refrigerant circuit, the shutoff valve of the gas refrigerant connection pipe having the minimum pipe diameter and included in the second refrigerant circuit, the shutoff valve of the gas refrigerant connection pipe having the maximum pipe diameter and included in the second refrigerant circuit, and the shutoff valve of the gas refrigerant connection pipe having the maximum pipe diameter and included in the first refrigerant circuit may be arranged in line in order from the top without any other shutoff valve that lies between the shutoff valves, or may be arranged in line in order from the top while another shutoff valve lies between the shutoff valves.

Note that the heat source-side unit may be commonly used in the first refrigerant circuit and the second refrigerant circuit. The heat source-side unit commonly used in the first refrigerant circuit and the second refrigerant circuit is the heat source-side unit including part of each of the first refrigerant circuit and the second refrigerant circuit independent of each other, and for example, may be obtained by unitizing the heat source-side heat exchanger belonging to the first refrigerant circuit and the heat source-side heat exchanger belonging to the second refrigerant circuit, or may be obtained by unitizing the compressor belonging to the first refrigerant circuit and the compressor belonging to the second refrigerant circuit. Here, the heat source-side heat exchanger belonging to the first refrigerant circuit and the heat source-side heat exchanger belonging to the second refrigerant circuit may be separate heat exchangers having separate heat transfer fins, or the heat source-side heat exchangers may have a common heat transfer fin.

Note that if a plurality of “gas refrigerant connection pipes having the maximum pipe diameter” is present in the refrigerant cycle system, an arbitrary one of the pipes can correspond to the “gas refrigerant connection pipe having the maximum pipe diameter”.

The first compressor may be a compressor having the largest capacity of the plurality of compressors provided in the refrigerant cycle system. If a plurality of “compressors having the maximum capacity” is present in the refrigerant cycle system, an arbitrary one of the compressors can correspond to the “compressor having the maximum capacity”.

Note that the sum of pipe diameters of the gas refrigerant connection pipes connected to the refrigerant circuit including the compressor having the maximum capacity in the refrigerant cycle system may be larger than the sum of pipe diameters of the gas refrigerant connection pipes connected to the refrigerant circuit including the compressor other than the compressor having the maximum capacity in the refrigerant cycle system. Here, when the plurality of refrigerant circuits including the compressor having the maximum capacity is present, the “sum of pipe diameters of the gas refrigerant connection pipes” may be an average of the sum of pipe diameters of the gas refrigerant connection pipes in each refrigerant circuit including the compressor having the maximum capacity. The average may be compared with the sum of pipe diameters of the gas refrigerant connection pipes connected to the refrigerant circuit including the compressor other than the compressor having the maximum capacity in each refrigerant circuit including the compressor other than the compressor having the maximum capacity.

Note that the heat source-side unit may be commonly used in the first refrigerant circuit and the second refrigerant circuit. The heat source-side unit commonly used in the first refrigerant circuit and the second refrigerant circuit is the heat source-side unit including part of each of the first refrigerant circuit and the second refrigerant circuit independent of each other, and for example, may be obtained by unitizing the heat source-side heat exchanger belonging to the first refrigerant circuit and the heat source-side heat exchanger belonging to the second refrigerant circuit, or may be obtained by unitizing the compressor belonging to the first refrigerant circuit and the compressor belonging to the second refrigerant circuit.

Note that the refrigerant cycle system does not have to include two or more types of pipe diameter as the plurality of gas refrigerant connection pipes, and the pipe diameter of all the gas refrigerant connection pipes may be the same.

Note that the sum of pipe diameters of the gas refrigerant connection pipes connected to the refrigerant circuit including the compressor having the maximum capacity in the refrigerant cycle system may be larger than the sum of pipe diameters of the gas refrigerant connection pipes connected to the refrigerant circuit including the compressor other than the compressor having the maximum capacity in the refrigerant cycle system. Here, when the plurality of refrigerant circuits including the compressor having the maximum capacity is present, the “sum of pipe diameters of the gas refrigerant connection pipes” may be an average of the sum of pipe diameters of the gas refrigerant connection pipes in each refrigerant circuit including the compressor having the maximum capacity. The average may be compared with the sum of pipe diameters of the gas refrigerant connection pipes connected to the refrigerant circuit including the compressor other than the compressor having the maximum capacity in each refrigerant circuit including the compressor other than the compressor having the maximum capacity.

The first compressor may be a compressor having the largest capacity of the plurality of compressors provided in the refrigerant cycle system. If a plurality of “compressors having the maximum capacity” is present in the refrigerant cycle system, an arbitrary one of the compressors can correspond to the “compressor having the maximum capacity”.

Note that the heat source-side heat exchanger common to the first refrigerant circuit and the second refrigerant circuit can be, for example, a heat source-side heat exchanger in which the refrigerant flow path flowing through part of the first refrigerant circuit and the refrigerant flow path flowing through part of the second refrigerant circuit are coupled via the common heat transfer fin.

Note that the first heat transfer tubes and the second heat transfer tubes may be arranged to overlap each other or may be arranged not to overlap each other in the air flow direction.

Note that in the heat source-side heat exchanger, at least two or more of the plurality of second heat transfer tubes may be arranged on a downwind side of any one of the plurality of first heat transfer tubes, and at least two or more of the plurality of first heat transfer tubes may be arranged on a windward side of any one of the plurality of second heat transfer tubes. In the heat source-side heat exchanger, there may be no second heat transfer tube arranged on a windward side of the plurality of first heat transfer tubes.

(Supplementary Note)

Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present disclosure. Accordingly, the scope of the disclosure should be limited only by the attached claims.

REFERENCE SIGNS LIST

-   -   1: air conditioning apparatus (refrigerant cycle system)     -   2: outdoor unit (heat source-side unit)     -   6: first indoor unit (first use-side unit)     -   7: second indoor unit (first use-side unit)     -   8: third indoor unit (second use-side unit)     -   9: fourth indoor unit (second use-side unit)     -   10: first refrigerant circuit     -   11: first compressor (compressor)     -   18 a: first gas-side shutoff valve (shutoff valve)     -   18 b: second gas-side shutoff valve (shutoff valve)     -   20: second refrigerant circuit     -   21: second compressor (compressor)     -   28 a: third gas-side shutoff valve (shutoff valve)     -   28 b: fourth gas-side shutoff valve (shutoff valve)     -   30: outdoor heat exchanger (heat source-side heat exchanger)     -   30 a: outdoor fan (heat source-side fan)     -   30 x: first outdoor heat exchange unit (first heat source-side         heat exchange unit)     -   30 y: second outdoor heat exchange unit (second heat source-side         heat exchange unit)     -   31: first heat transfer tube     -   32: second heat transfer tube     -   33: heat transfer fin     -   34: first gas header     -   35: second gas header     -   36: first distributor     -   37: second distributor     -   50: control unit     -   61: first indoor heat exchanger (first use-side heat exchanger)     -   65: first liquid-side refrigerant connection pipe (first liquid         refrigerant connection pipe)     -   66: first gas-side refrigerant connection pipe (first gas         refrigerant connection pipe, gas refrigerant connection pipe)     -   71: second indoor heat exchanger (first use-side heat exchanger)     -   75: second liquid-side refrigerant connection pipe (first liquid         refrigerant connection pipe)     -   76: second gas-side refrigerant connection pipe (first gas         refrigerant connection pipe, gas refrigerant connection pipe)     -   81: third indoor heat exchanger (second use-side heat exchanger)     -   85: third liquid-side refrigerant connection pipe (second liquid         refrigerant connection pipe)     -   86: third gas-side refrigerant connection pipe (second gas         refrigerant connection pipe, gas refrigerant connection pipe)     -   91: fourth indoor heat exchanger (second use-side heat         exchanger)     -   95: fourth liquid-side refrigerant connection pipe (second         liquid refrigerant connection pipe)     -   96: fourth gas-side refrigerant connection pipe (second gas         refrigerant connection pipe, gas refrigerant connection pipe)     -   230 x: first outdoor heat exchanger (first heat source-side heat         exchange unit)     -   230 y: second outdoor heat exchanger (second heat source-side         heat exchange unit)

PATENT LITERATURE

-   PATENT LITERATURE 1: JP 2011-257097 A -   PATENT LITERATURE 2: JP 2009-174759 A 

What is claimed is:
 1. A refrigerant cycle system comprising: a first refrigerant circuit; a second refrigerant circuit independent of the first refrigerant circuit; a heat source-side unit that comprises: a first heat source-side heat exchange unit; and a second heat source-side heat exchange unit; a first use-side unit that comprises: a first use-side heat exchanger; a first liquid refrigerant connection pipe and a first gas refrigerant connection pipe that connect the first use-side unit to the heat source-side unit; a second use-side unit that comprises: a second use-side heat exchanger; and a second liquid refrigerant connection pipe and a second gas refrigerant connection pipe that connect the second use-side unit to the heat source-side unit, wherein the first refrigerant circuit is constituted by: the first heat source-side heat exchange unit; the first use-side heat exchanger; the first liquid refrigerant connection pipe; and the first gas refrigerant connection pipe, the second refrigerant circuit is constituted by: the second heat source-side heat exchange unit; the second use-side heat exchanger; the second liquid refrigerant connection pipe; and the second gas refrigerant connection pipe, and a refrigerant classified by ISO817 as lower flammability (A2L) is disposed in each of the first refrigerant circuit and the second refrigerant circuit.
 2. The refrigerant cycle system according to claim 1, wherein the first heat source-side heat exchange unit further comprises first heat transfer tubes, the first refrigerant circuit is further constituted by the first heat transfer tubes, the second heat source-side heat exchange unit further comprises second heat transfer tubes, the second refrigerant circuit is further constituted by the second heat transfer tubes, and a heat source-side heat exchanger comprises: the first heat source-side heat exchange unit; the second heat source-side heat exchange unit; and a heat transfer fin through which both the first heat transfer tubes and the second heat transfer tubes penetrate.
 3. The refrigerant cycle system according to claim 2, wherein one or more of the second heat transfer tubes are disposed on a downwind side of any one of the first heat transfer tubes.
 4. The refrigerant cycle system according to claim 3, wherein half or more of the second heat transfer tubes are disposed on the downwind side of any one of the first heat transfer tubes.
 5. The refrigerant cycle system according to claim 2, wherein one or more of the second heat transfer tubes are disposed on a windward side of any one of the first heat transfer tubes.
 6. The refrigerant cycle system according to claim 2, wherein the heat source-side unit further comprises a heat source-side fan that supplies an air flow to the heat source-side heat exchanger.
 7. The refrigerant cycle system according to claim 1, wherein the refrigerant comprises R32.
 8. The refrigerant cycle system according to claim 1, wherein the refrigerant is a non-azeotropic mixed refrigerant.
 9. The refrigerant cycle system according to claim 1, wherein the refrigerant consists of one or more of R454A, R454B, and R454C.
 10. The refrigerant cycle system according to claim 1, wherein the first liquid refrigerant connection pipe and the second liquid refrigerant connection pipe have an outer diameter of 6.35 mm and an inner diameter of less than 4.75 mm.
 11. The refrigerant cycle system according to claim 1, wherein the first gas refrigerant connection pipe has a different diameter from the second gas refrigerant connection pipe has.
 12. The refrigerant cycle system according to claim 11, wherein the first liquid refrigerant connection pipe has a different diameter from the second liquid refrigerant connection pipe has.
 13. The refrigerant cycle system according to claim 11, wherein the first refrigerant circuit is further constituted by a third gas refrigerant connection pipe that has a different pipe diameter from the first gas refrigerant connection pipe has, the second refrigerant circuit is further constituted by a fourth gas refrigerant connection pipe that has a different pipe diameter from the second gas refrigerant connection pipe has, in the heat source-side unit, a shutoff valve of one of gas refrigerant connection pipes in the first refrigerant circuit that has a minimum pipe diameter is disposed lower than a shutoff valve of one of gas refrigerant connection pipes in the second refrigerant circuit that has a minimum pipe diameter, a shutoff valve of one of the gas refrigerant connection pipes in the second refrigerant circuit that has a maximum pipe diameter is disposed lower than the shutoff valve of the one of the gas refrigerant connection pipes in the first refrigerant circuit that has the minimum pipe diameter, and a shutoff valve of one of the gas refrigerant connection pipes in the first refrigerant circuit that has a maximum pipe diameter is disposed lower than the shutoff valve of the one of the gas refrigerant connection pipes in the second refrigerant circuit that has the maximum pipe diameter.
 14. The refrigerant cycle system according to claim 11, wherein the first refrigerant circuit is further constituted by a third gas refrigerant connection pipe that has a different pipe diameter from the first gas refrigerant connection pipe has, the second refrigerant circuit is further constituted by a fourth gas refrigerant connection pipe that has a different pipe diameter from the second gas refrigerant connection pipe has, in the heat source-side unit, a shutoff valve of one of gas refrigerant connection pipes in the second refrigerant circuit that has a minimum pipe diameter is disposed lower than a shutoff valve of one of gas refrigerant connection pipes in the first refrigerant circuit that has a minimum pipe diameter, a shutoff valve of one of the gas refrigerant connection pipes in the second refrigerant circuit that has a maximum pipe diameter is disposed lower than the shutoff valve of the one of the gas refrigerant connection pipes in the second refrigerant circuit that has the minimum pipe diameter, and a shutoff valve of one of the gas refrigerant connection pipes in the first refrigerant circuit that has a maximum pipe diameter is disposed lower than the shutoff valve of the one of the gas refrigerant connection pipes in the second refrigerant circuit that has the maximum pipe diameter.
 15. The refrigerant cycle system according to claim 11, wherein the first refrigerant circuit and the second refrigerant circuit are each constituted by a compressor that has an equal capacity.
 16. The refrigerant cycle system according to claim 1, wherein the first refrigerant circuit is further constituted by a first compressor, the second refrigerant circuit is further constituted by a second compressor that has a smaller capacity than the first compressor has, and the first gas refrigerant connection pipe has a larger pipe diameter than the second gas refrigerant connection pipe has.
 17. The refrigerant cycle system according to claim 16, wherein a sum of pipe diameters of all of gas refrigerant connection pipes in the first refrigerant circuit is greater than a sum of pipe diameters of all of gas refrigerant connection pipes in the second refrigerant circuit.
 18. The refrigerant cycle system according to claim 1, wherein the first refrigerant circuit is further constituted by a first compressor, the second refrigerant circuit is further constituted by a second compressor that has a smaller capacity than the first compressor has, the first gas refrigerant connection pipe has a different pipe diameter than the second gas refrigerant connection pipe has, and a sum of pipe diameters of all of gas refrigerant connection pipes in the first refrigerant circuit is greater than a sum of pipe diameters of all of gas refrigerant connection pipes in the second refrigerant circuit.
 19. The refrigerant cycle system according to claim 16, wherein the heat source-side unit comprises a heat source-side heat exchanger that is common to the first refrigerant circuit and the second refrigerant circuit, the heat source-side heat exchanger comprises: first heat transfer tubes belonging to the first refrigerant circuit; and second heat transfer tubes belonging to the second refrigerant circuit, and a number of the first heat transfer tubes is greater than a number of the second heat transfer tubes.
 20. The refrigerant cycle system according to claim 19, wherein in the heat source-side heat exchanger, one or more of the second heat transfer tubes are disposed on a downwind side of any one of the first heat transfer tubes.
 21. The refrigerant cycle system according to claim 19, further comprising a control unit that executes: an operation in a cooling cycle in the first refrigerant circuit, and an operation in a heating cycle in the second refrigerant circuit simultaneously. 